A cold front stalled along the Laramie Range and combined with a strong pressure gradient and produced gusty winds across the area.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CYS wrote it up.
A cold front stalled along the Laramie Range and combined with a strong pressure gradient and produced gusty winds across the area.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Cheyenne, WY wrote its last area forecast discussion before the first event at Feb 20, 10:01 PM MST, 4 hours 5 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CHEYENNE WY 1001 PM MST SUN FEB 20 2011 .UPDATE...TONIGHT... TEMPERATURES IN SOME AREAS ALONG THE SOUTHERN LARAMIE RANGE HAVE ALREADY DROPPED BELOW PREVIOUSLY EXPECTED OVERNIGHT LOWS SO HAVE ADJUSTED THESE VALUES BASED ON THE LATEST TRENDS. IN ADDITION...PRECIPITATION BAND HAS SET UP AS IS TYPICAL IN THE NORTHWEST FLOW ON THE BACK OF A DEPARTING STORM SYSTEM AND THIS AREA OF LIGHT SNOW WILL LIKELY CONTINUE THROUGH AROUND 3 AM MST BEFORE DIMINISHING EARLY PRESIDENTS DAY. WEBCAMS AT SNOWY RANGE SKI AREA AND NEAR ALBANY INDICATE THAT AT LEAST LIGHT SNOW CONTINUES THERE THIS EVENING...BUT THE OBSERVATION FROM NEAR DIXON HAS NOT BEEN INDICATING SNOWFALL THIS EVENING. BELIEVE THE MOUNTAINS...AT LEAST THE HIGHER ELEVATIONS...WILL CONTINUE TO SEE SNOWFALL OVERNIGHT WITH ONLY LIGHT ACCUMULATIONS EXPECTED OVERNIGHT. WINDS HAVE STARTED TO REBOUND AGAIN NEAR ARLINGTON SO WILL LEAVE THE HIGH WIND WARNING IN PLACE THROUGH 8 AM MST PRESIDENTS DAY...MONDAY...MORNING. && .AVIATION...06Z TAF ISSUANCE... IFR CEILINGS AND VISIBILITIES WILL CONTINUE BENEATH THE BAND OF PRECIPITATION FROM AROUND CASPER SOUTHEAST INTO THE SOUTHERN NEBRASKA PANHANDLE. SNOW SHOWERS WILL CONTINUE IN THE MOUNTAINS AND WILL CREATE CONTINUED MOUNTAIN OBSCURATION OVERNIGHT. AWAY FROM THE MOUNTAINS AND THE BAND OF PRECIPITATION...VFR CONDITIONS ARE GENERALLY EXPECTED OVERNIGHT. && PREV DISCUSSION... /ISSUED 447 PM MST SUN FEB 20 2011/ UPDATE...UPDATED THE TONIGHT FORECAST TO ALLOW THE WINTER WEATHER ADVISORY TO EXPIRE. STILL EXPECT LIGHT SNOW ACROSS WYOMING THIS EVENING...ESPECIALLY ACROSS NORTHERN CARBON COUNTY EASTWARD TO NORTHERN ALBANY AND CONVERSE COUNTIES. SNOW HAS STARTED TO DECREASE IN INTENSITY WITH KRIW RADAR NOT AS IMPRESSIVE AS IT WAS EARLIER WHEN DOUGLAS REPORTED ONE QUARTER TO ONE HALF MILE VISIBILITIES IN MODERATE SNOW. ANOTHER INCH OR TWO OF SNOW IS POSSIBLE IN THESE AREAS UNTIL THE SNOW TAPERS TO FLURRIES BY LATE THIS EVENING. FURTHER SOUTH...CURRENT RADAR SHOWS A BAND OF LIGHT SNOW PUSHING SLOWLY SOUTHEASTWARD ACROSS PLATTE...GOSHEN...AND LARAMIE COUNTIES WHERE UP TO ONE INCH OF ADDITIONAL SNOW ACCUMULATION IS POSSIBLE. IN ADDITION...EXTENDED THE HIGH WIND WARNING AT ARLINGTON BETWEEN RAWLINS AND LARAMIE UNTIL 8 AM TOMORROW MORNING WITH WINDS CONTINUING TO GUST UP TO 60 MPH AT ARLINGTON AND ELK MOUNTAIN. TT PREV DISCUSSION... /ISSUED 240 PM MST SUN FEB 20 2011/ SHORT TERM...TONIGHT THROUGH TUESDAY CURRENT RADAR LOOP ACROSS WYOMING AND SOUTHWEST SOUTH DAKOTA SHOW SNOWFALL CONTINUING NORTH OF CHEYENNE TOWARDS RAWLINS AND DOUGLAS WITH A HALF MILE VISIBILITY REPORTED AT DOUGLAS THE LAST SEVERAL HOURS IN MODERATE SNOW. RAWLINS AND LUSK HAVE REPORTED LIGHT SNOW THROUGH THE DAY AS WELL WITH WEB CAMS SHOWING SNOW COVERED ROADWAYS ALONG PORTIONS OF I-25 AND MOST OF I-80 WEST OF LARAMIE. WILL CONTINUE THE WINTER WEATHER ADVISORY THROUGH THE AFTERNOON ACROSS WYOMING. WILL CANCEL THE WINTER WEATHER ADVISORY FOR THE REST OF NEBRASKA AND NIOBRARA COUNTY WITH KUDX RADAR SHOWING THE SNOW DIMINISHING ACROSS THE AREA. WILL KEEP THE HIGH WIND WARNING GOING FOR THE ARLINGTON AREA ALONG I-80 FOR SUSTAINED WINDS BETWEEN 30 TO 45 MPH WITH GUSTS AROUND 55 MPH. WILL NEED TO REEVALUATE THE SITUATION LATER AND MAY NEED TO EXTEND THE HIGH WIND WARNING THROUGH TONIGHT IF WINDS DO NOT SUBSIDE SHORTLY. MODELS IN GOOD AGREEMENT THROUGH EARLY THIS WEEK. THE STORM SYSTEM THAT BROUGHT SNOW AND ICY PRECIP TO THE REGION THIS WEEKEND WILL CONTINUE TO PUSH EASTWARD INTO THE GREAT LAKES RESULTING IN ZONAL FLOW AND SLOWLY WARMING TEMPERATURES ON MONDAY. HIGH TEMPS WILL STILL BE 5 TO 15 DEGREES BELOW NORMAL ON MONDAY WITH HIGHS IN THE 20S AND 30S. OUTSIDE OF MOUNTAIN SNOW SHOWERS...DRIER WEATHER IS EXPECTED MONDAY. ATTENTION THEN SHIFTS TO STRONG WINDS ACROSS WYOMING AND BLOWING SNOW BY MONDAY NIGHT AND EARLY TUESDAY. CURRENT MODELS ALL SHOW A STRENGTHENING PRESSURE GRADIENT AT THE SURFACE AND AT 700MB WEST OF THE NEBRASKA BORDER...WHICH WILL RESULT IN WINDY CONDITIONS ACROSS MOST OF SOUTHEAST WYOMING. WILL LIKELY NEED A HIGH WIND WATCH IN THE NEXT 12 TO 18 HOURS FOR THE MORE WIND PRONE AREAS INCLUDING BORDEAUX...ARLINGTON...AND POSSIBLY THE SOUTHERN LARAMIE RANGE FOR GUSTS UP TO 65 MPH. EVEN LOCATIONS SUCH AS RAWLINS...LARAMIE...AND CHEYENNE MAY SEE GUSTS AROUND 50 MPH AS WELL. INCLUDED BLOWING SNOW IN THE FORECAST DUE TO RECENT SNOWFALL NORTHWEST OF LARAMIE TOWARDS RAWLINS. OTHERWISE WITH WESTERLY DOWNSLOPE WINDS...EXPECT TEMPS TO RETURN TO NEAR NORMAL...WITH 30S WEST TO 40S OVER THE HIGH PLAINS BY TUESDAY AFTERNOON. MODELS THEN SHOW OUR NEXT STORM SYSTEM PUSHING SOUTHEAST ACROSS THE NORTHERN ROCKIES AND PACIFIC NORTHWEST LATE TUESDAY. LONG TERM...TUESDAY NIGHT THROUGH SUNDAY THE 12Z NUMERICAL MODELS ARE SIMILAR IN THEIR HANDLING OF THE MID/UPPER LEVELS INITIALLY. CLOSED UPPER LOW OFF THE SOUTHERN CA COAST OPENS INTO A WAVE AS IT CROSSES THE BAJA PENINSULA LATE TUESDAY NIGHT AND THEN SHEARS QUICKLY TO THE NORTHEAST OVER THE SOUTHERN PLAINS LATE WEDNESDAY. WESTERLY WIND FLOW ALOFT WILL BE OVER THE CWA TUESDAY NIGHT THEN BACK TO SOUTHWEST ON WEDNESDAY IN ADVANCE OF THE NEXT SHORTWAVE TROUGH APPROACHING FROM THE NORTHWEST. A SURFACE LOW PRESSURE TROUGH WILL BE OVER THE EASTERN CWA. 700 MB WIND PROGS SHOW 50 TO 60 KT WINDS TUESDAY NIGHT AND WEDNESDAY MORNING OVER SOUTHEAST WYOMING. WINDY CONDITIONS WILL DEVELOP...MAINLY ALONG AND WEST OF THE LARAMIE RANGE...WHERE WIND GUSTS COULD REACH AS HIGH AS 55 MPH. HIGH TEMPERATURES ON WEDNESDAY WILL BE IN THE 30S AND 40S...WITH 20S IN THE MOUNTAINS. THE WEATHER PATTERN WILL REVERT BACK TO A PROLONGED PERIOD OF BELOW NORMAL TEMPERATURES AND DAILY SNOW CHANCES BEGINNING WEDNESDAY NIGHT. THE 12Z MODELS DIFFER WITH THE GENERAL CONSENSUS FOLLOWING THE GFS AND GEM IN MOVING THE SHORTWAVE TROUGH FROM THE PACIFIC NORTHWEST FRIDAY ACROSS THE CWA NEXT WEEKEND. THE ECMWF MAINTAINS THE TROUGH AXIS OVER OR JUST WEST OF THE CWA WITH A WESTERLY FLOW ALOFT. A WEAK PACIFIC COLD FRONT MOVES ACROSS THE CWA TUESDAY NIGHT...FOLLOWED BY A STRONGER COLD FRONT WEDNESDAY NIGHT. THE FRONT BECOMES STATIONARY WEST OF THE LARAMIE RANGE THURSDAY THROUGH SATURDAY. ALONG AND EAST OF THE BOUNDARY IT WILL BE COLDER...WITH PERIODS OF LIGHT SNOW AND FOG. THE CANADIAN SURFACE RIDGE BUILDS SOUTH FRIDAY AND SATURDAY...RESULTING IN COLDER TEMPERATURES. HIGHS IN THE TEENS AND 20S WITH LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO ARE FORECAST BOTH FRIDAY AND SATURDAY. THE COLD SURFACE HIGH SHIFTS EAST INTO THE PLAINS SUNDAY WITH THE NEXT SHORTWAVE TROUGH MOVING ACROSS WYOMING AND COLORADO. SNOW CHANCES WILL TAPER OFF BY SUNDAY NIGHT. FIRE WEATHER... NO CONCERNS ANTICIPATED THROUGH EARLY THIS WEEK WITH MODERATE TO HIGH HUMIDITIES...COLDER TEMPERATURES...AND SNOWFALL TONIGHT. COLDER THAN NORMAL CONDITIONS AND ANOTHER CHANCE OF ACCUMULATING SNOW IS EXPECTED BY THE END OF THE WEEK. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...HIGH WIND WARNING UNTIL 8 AM MONDAY FOR WYZ110. NE...NONE. && UPDATE/CARPENTER...CARPENTER SHORT TERM/FIRE WEATHER...TJT LONG TERM...JAMSKI
HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE CHEYENNE WY 947 PM MST SUN FEB 20 2011 NEZ002-003-019>021-054-055-095-096-WYZ101>119-220500- DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE- NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS- NIOBRARA COUNTY-NORTH LARAMIE RANGE- FERRIS/SEMINOE/SHIRLEY MOUNTAINS-SHIRLEY BASIN- CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY- EAST PLATTE COUNTY-GOSHEN COUNTY-CENTRAL CARBON COUNTY- NORTH SNOWY RANGE FOOTHILLS-SOUTHWEST CARBON COUNTY- SIERRA MADRE RANGE-UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE- LARAMIE VALLEY-SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS- CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY- 947 PM MST SUN FEB 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA PANHANDLE...EAST CENTRAL WYOMING...SOUTH CENTRAL WYOMING AND SOUTHEAST WYOMING. .DAY ONE...TONIGHT A HIGH WIND WARNING REMAINS IN EFFECT FOR THE ARLINGTON AREA...ALONG INTERSTATE 80...THROUGH 8 AM MST MONDAY MORNING. LIGHT SNOW WILL CONTINUE ACROSS THE NORTH LARAMIE RANGE SOUTHEAST TO THE SOUTHERN NEBRASKA PANHANDLE THROUGH AROUND 3 AM MST MONDAY MORNING...WITH LITTLE ADDITIONAL ACCUMULATION EXPECTED. ADDITIONAL ACCUMULATIONS OF 1 TO 2 INCHES WILL OCCUR ACROSS THE MOUNTAINS OF THE SNOWY RANGE AND SIERRA MADRE RANGE OVERNIGHT. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY WESTERLY WINDS WILL GUST AS HIGH AS 50 MPH TUESDAY AND WEDNESDAY MORNING IN AREAS OVER AND NEAR THE LARAMIE RANGE IN WYOMING. COLD TEMPERATURES AND A GOOD CHANCE OF FOG AND ACCUMULATING SNOW WILL RETURN TO SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE WEDNESDAY NIGHT THROUGH SATURDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT. && THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT... HTTP://WEATHER.GOV/CHEYENNE CARPENTER
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
WYDOT sensor at Arlington measured sustained winds in excess of 40 mph with a peak gust of 64 mph at 21/0656 AM.
WYDOT sensor at Vedauwoo measured sustained winds in excess of 40 mph.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wyoming in 2011Every state in 2011This day in weather historyWarnings in Wyoming, February 2011
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 276880, 276883.